There are a number of commercial applications that utilizes a controlled gas atmosphere enclosure. For example, in the semiconductor industry, gases are injected into an enclosed chamber wherein one of the gases are plasmarized causing the gas to hit a target on a chamber lid causing the target's materials to deposit on a wafer. Other commercial applications include using controlled gasses to cultivate biological cultures in an enclosed chamber such as an incubator. It is desirable to maintain optimal conditions inside the incubator in order to promote the desired growth of the cultures. In a conventional incubator, gasses such as O2, N2, and CO2 are introduced from their respective tanks into the chamber depending on the growing conditions desired. Typically, the user sets the CO2 and O2 setpoints and appropriate gas are added, if needed.
A conventional incubator is generally rectangular in shape and has up to five insulated walls (top, bottom, left side, right side, and rear). Each wall may have an inner space defined by the inner and outer surfaces of the insulated wall and the inner spaces are in communication with each other. An insulated front door together with the insulated walls complete the inner chamber of the incubator and the door is typically mounted on hinges on the front side of one of the side walls. The door allows access into the inner chamber where culture plates are placed or removed from a plethora of shelves provided therein.
Most biological incubators are either water jacket or forced draft. In the water jacket incubator, a water jacket is inserted in the inner space of the incubator. A heater is used to heat the water in the water jacket to the desired temperature. Because water can be heated evenly, the water jacket can evenly distribute the desired heat throughout the inner chamber. Such even heating is desired in order to provide a uniform temperature (for the biological cultures) throughout the chamber and to prevent “cold spots,” which can cause condensation on the inner chamber walls.
Although heating of the chamber walls in the water jacket incubator is substantially uniform, the chamber atmosphere will stratify thermally if the chamber atmosphere is undisturbed. Due to the stratification, the temperature of the chamber is greater at the top of the chamber than at the bottom of the chamber. Consequently, if a constituent gas such as CO2 is maintained in the chamber, the CO2 will also stratify and the desired atmosphere for the cultures will not be maintained. Therefore, it is desirable to maintain a certain flow rate of constituent gases within the chamber to assure uniformity of the temperature and the constituent gas.
In order to circulate the air, a portion of the inner chamber is separated from the rest of the chamber by a wall to define a duct extending along the side of the chamber. The duct has an upper portion or the duct inlet, where a fan or a blower is used to circulate the air in the chamber and a lower portion (duct outlet) where air exits the chamber to be recirculated.
In the forced draft incubator, the inner space is lined with insulation instead of the water jacket. Heating of the chamber is provided by having a duct (previously described), a fan, and a heating element within the chamber. The air is typically circulated by the fan and heated by the heating element within the duct. The air is blown with more force than in the water jacket incubators in order to have more uniform circulation of the air and temperature in the chamber.
In most cases for proper culture growth, it is desirable to maintain a certain level of CO2 and O2 in the chamber. Thus, the O2 enhancement levels or depletion changes dynamically depending on the CO2 concentration. In order to maintain constituent gas levels such as CO2 in conventional incubators, a probe can be inserted into the chamber to take a measurement of the gas level including CO2, O2. Based on the CO2 setpoint selected by the user and the information from the probe, the user can determine if O2 is needed or if O2 needs to be purged by adding N2 to the incubator. In a conventional trigas incubator, where the two main gases to be controlled are CO2 and O2, there can be a CO2 tank connected to an inlet and O2 and N2 connected to another inlet. A manual switch can switch between the O2 and N2 tanks depending on the level of O2 desired in the incubator.
If the user, based on the information from the probe and the CO2 setpoint determines that O2 is needed by mistake, when N2 is really needed, the user can hook up the wrong tank. With the wrong tank in place, the wrong gas will be injected, thereby causing the results from the cultures to be inaccurate or possibly destroying weeks, or months worth of research. Additionally, if too much O2 is added, then an explosive situation can be created in the chamber.
Therefore, there is a need for a notification system to allow a user to know which tanks to attach to the incubator for a given setpoint of a gas for improved culture growth. Additionally, there is a need for a notification system that helps to prevent the user from hooking up the wrong tank.